Licheng Zhang,Jinfeng Li,Ruirui Liu,Yongquan Zhou,Yuze Zhang,Lianmin Ji,Lijuan Li
Efficient separation of lithium from salt lake brine with high Na/Li ratio is of great importance for the development of new energy industry. Liquid-liquid extraction using β-diketone system was proved to be an effective approach to separate lithium from alkaline metal ions, while the separation effect of lithium to alkali earth ions needs further investigation. In this work we proposed an extraction process using HBTA/TRPO system to recovery lithium from salt lake brine with high Na/Li ratio. The conditions of saponification, extraction, eluting, stripping and regeneration process was optimized by equilibrium experiments. Through the process, lithium, calcium and magnesium were extracted to the organic phase and then stripped step by step to obtain lithium-rich solution, then the stability of the process and organic was tested by cycle experiments, the results indicated the proposed method was effective and stable. Theoretical study based on density functional theory was conducted to expound the extraction selectivity to different metal ions, and the energy change, electrostatic potential and Mulliken charge of the complexes was obtained, the calculated results suggested the stability of the complexes followed the sequence: Mg 2+ > Ca 2+ > Li + > Na + > K + , which is consistent with the experimental results. The present work may provide a novel way to efficiently recover lithium from salt lake brine with high Na/Li ratio.
Lin-Pei Guo,Zhi-Yuan Guo,Jing Wang,Pan-Pan Zhang,Zhi-Hui Huang,Zhi-Yong Ji
Monovalent selective ion-exchange membranes have been widely used for lithium extraction from brine with a high Mg/Li ratio. However, extracting Li + directly from raw brine with high Na/Li ratio remains a significant challenge. This study introduces a flexible lithium selective composite membrane by incorporating lithium-ion conductor with a quaternized polymer. The lithium-ion conductor provides pathways for lithium transmission, while the quaternized polymer effectively hinders the leakage of impurity cations. As a result, with the applied voltage of 2.0 V, the membrane achieved a high Li + /Na + separation coefficient of 35.48 with a Li + flux of 8.33 × 10 −10 mol cm −2 s −1 in the simulated Yiliping brine, which are 56.3 and 2.8 times higher than that of commercial monovalent selective cation exchange membrane (CIMS). We proposed a lithium transport mechanism involving an adsorption-dehydration-diffusion process through the membrane. Theoretical calculations indicate that the combined effects of significant adsorption energy (−0.47 eV), low dehydration energy (515 kJ mol −1 ), and low diffusion barrier (0.37 eV) leads to the high selectivity for lithium. These findings provide promising prospects for the large-scale preparation of lithium ion-selective membranes, enabling the direct lithium extraction from raw brine.
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